Method of manufacturing a reinforced film

Claim 1

A continuous process for manufacturing a non-porous, reinforced, impervious, unitary film, said process comprising the steps of: providing a low viscosity impregnating liquid comprising a thermoformable plastic having a sufficiently high percentage of solids to liquids so that a non-porous unitary film is capable of being formed upon calendering; providing an open fabric having a plurality of yarns in a first direction and a plurality of yarns in a second direction at a substantial angle to the first; providing at least one lightweight, porous mat having a plurality of filaments; continuously feeding the fabric and the mat from respective feed ends to an exit end; impregnating the fabric and the mat with the impregnating liquid, the impregnating liquid flowing into the open fabric and the porous mat to impregnate the yarns of the fabric and to surround the filaments of the mat and to form a side by side impregnated combination of fabric and mat in which the weight of the thermoformable plastic carried on the impregnated combination is 100 to 800% measured as dry pickup weight relative to the combined weight of the fabric and the mat, which amount is sufficient to be deformed into a non-porous unitary film upon calendering, the mat bridging gaps between the yarns of the fabric; continuously setting the plastic of the impregnated combination of fabric and mat to eliminate essentially all carrier liquid by significantly reducing the viscosity and any tackiness of the plastic, and to form an impregnated combination of fabric, mat, and set plastic, the set, impregnated combination having gaps between the yarns of the fabric bridged by mat impregnated with set plastic and having a predetermined porosity; and continuously deforming the set, impregnated combination of plastic, fabric, and may by calendering with a heated calender roll of sufficient heat and at a sufficient pressure gradient to deform the plastic to further impregnate and surround the yarns of the fabric and filaments of the mat with the plastic and to close essentially all remaining pores and voids in the impregnated combination, to create a non-porous, impervious, continuous, low-wicking, essentially void-free, unitary film having a reinforcement of fabric and mat embedded therein.